[T3] Why early clocks fail

Tue Aug 9 08:13:10 PDT 2011

Your connecting technique is correct.  I pulled the clock out of my ’73 Squareback and had it repaired.  When I tested it on the bench by hooking it to a battery, it would initially start and then slowly stop.  The correct method appears to be to initially connect it for a second or two, disconnect it and then reconnect it.  Using this procedure it will continue to run.  My clock tends to run fast. The repairing agency also indicated that this reconnect procedure is correct. In the future if I have to remove the battery I will re-start the clock by temporarily connecting the battery, remove the connection and then re-connect. 

-----Original Message-----
>From: Jeremy Menzies <skellzangelz at hotmail.com>
>Sent: Aug 9, 2011 12:40 PM
>To: type3 at vwtype3.org
>Subject: Re: [T3] Why early clocks fail
>
>
>I never knew about the sitting battery causing that little wire to blow but that makes sense after seeing the mechanism in my clock (which is in my '71).  I was talking with a guy who used to have a Mercedes shop about it and he told me a trick they used to do for the same type of electrically wound mechanical clocks in the Mercedes.  He said to tap the negative terminal just a bit (to make a spark) and then fully push it down onto the post, instead of just putting it straight on.  Reason being that he'd seen it happen where the little clock 'fuse' would blow out when you reconnected it if you didn't release the energy through the spark.  Who knows if that's really what was happening but I just thought it was interesting and hey, it's not going to hurt anything.  
>It's a pretty cool mechanism inside there, I decided to fix mine several months ago after seeing your write up about it on the T3 site.  I think I pulled a single strand of wire out of a cable and soldered it in there but never thought about the diode.  Mine typically runs at least 5-10 min slower than my tape player or phone clock, so I constantly have to reset it if I actually want to know what time it is.  It's nice to have it working and hear the clunk every time the solenoid rewinds it, though...
>I second the disconnect the battery and get it on an automatic slow charger, I work at a battery store and probably 90% of the people who come in to replace their dead batteries left it sit for too long without a charger.  I even recommend doing it if you drive infrequently or for only short trips (especially with the older 30A generator), you'll get much longer battery life if it's kept charged!
>-Jeremy
>
>
>> From: jadney at vwtype3.org
>> To: type3 at vwtype3.org
>> Date: Tue, 9 Aug 2011 08:24:44 -0500
>> Subject: Re: [T3] Why early clocks fail
>> 
>> Sure, I've got one car on a "maintainer" right now.
>> 
>> On 9 Aug 2011 at 8:22, crash 69 wrote:
>> 
>> > So using a trickle charger would be OK, right?
>> > 
>> > On Mon, Aug 8, 2011 at 9:41 PM, Jim Adney <jadney at vwtype3.org> wrote:
>> > 
>> > > I just fixed an early (up thru '70, the ones with the white plastic
>> > > backs) clock for someone who asked what goes wrong with them. I
>> > > thought this might be worth sharing with everyone.
>> > >
>> > > These early clocks use a solenoid to wind the clock every minute or
>> > > so. When the spring winds down a bit this lets a set of points make
>> > > contact, energizing a solenoid which "kicks" the winder and opens the
>> > > points. I believe this is typical for all car clocks up to around
>> > > 1970.
>> > >
>> > > There's a "fuse" in these clocks that opens up. This typically
>> > > happens if the car is left in storage with the battery installed. As
>> > > the battery discharges, it gets to the point where no longer
>> > > sufficient voltage to kick the winder, so the points stay closed and
>> > > draw current continuously until the fuse blows. The clock normally
>> > > draws current for only a fraction of a second, and that current
>> > > normally never gets large enough (or long enough) to trip the fuse.
>> > >
>> > > The "fuse" is actually a tiny rivet made of very low melting point
>> > > solder. I repair it by melting it and rejoining the connection. I
>> > > also add a diode across the solenoid to minimize arcing when the
>> > > points open. Then I flush out the works and lubricate each of the
>> > > pivots with clock oil. The repair is usually pretty straightforward,
>> > > but these clocks never kept very good time.
>> > >
>> > > In 40 years, I've only seen one of these clocks where the bearings &
>> > > pivots were actually worn out.
>> > >
>> > > The moral? Disconnect either the battery or the clock if you park the
>> > > car for a long time (months.)
>> > >
>> > >
>> > > --
>> > > *******************************
>> > > Jim Adney, jadney at vwtype3.org
>> > > Madison, Wisconsin, USA
>> > > *******************************
>> > >
>> > > _______________________________________________
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>> 
>> -- 
>> *******************************
>> Jim Adney, jadney at vwtype3.org
>> Madison, Wisconsin, USA
>> *******************************
>> 
>> _______________________________________________
>> VWType3.Org mailing list - type3 at vwtype3.org
>> http://lists.vwtype3.org/listinfo.cgi/type3-vwtype3.org
>> Contact gregm at vwtype3.org if you need help with the list.
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